Fix crash when an orphaned extension has a content script

Bug: 1036028
Change-Id: If402bda0f6532f1254a710223ff66bb77e0cf15f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2079530Reviewed-by: Devlin <rdevlin.cronin@chromium.org>
Commit-Queue: Evan Stade <estade@chromium.org>
Cr-Commit-Position: refs/heads/master@{#745633}

chrome/browser/extensions/user_script_listener.cc

@@ -237,6 +237,12 @@ void UserScriptListener::OnExtensionUnloaded(
   if (ContentScriptsInfo::GetContentScripts(extension).empty())
     return;  // No patterns to delete for this extension.
 
+  // It's possible to unload extensions before loading extensions when the
+  // ExtensionService uninstalls an orphaned extension. In this case we don't
+  // need to update |profile_data_|. See crbug.com/1036028
+  if (profile_data_.count(browser_context) == 0)
+    return;
+
   // Clear all our patterns and reregister all the still-loaded extensions.
   const ExtensionSet& extensions =
       ExtensionRegistry::Get(browser_context)->enabled_extensions();